AttributeError: lambdify(x, x/2, "mpmath")(I)

[ethankward]

>>> from sympy import *
>>> x = Symbol('x')
>>> lambdify(x, x/2, "mpmath")(I)
Traceback (most recent call last):
  File "test.py", line 35, in <module>
    print(lambdify(x, x/2, "mpmath")(I))
  File "<lambdifygenerated-1>", line 2, in _lambdifygenerated
  File "<string>", line 17, in __mul__
AttributeError: can't set attribute

Bisected to commit 952382d.